Grade 6: Life and living

Curriculum

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Food Processing

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Need for processing food

• food is processed to:
  • make it edible (preparing, cooking)
  • make it last longer (preserving)
  • improve its nutrient value (fermenting)
• during processing many foods may lose some of their nutrients

Methods for processing food

• there are many different methods (ways) to process food

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Suggested Activities

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• researching how to process food (raw material) by combining, cooking, freezing, pickling, fermenting, drying and salting to make a product, including indigenous ways of processing of food in different communities
• choosing a food and processing it in some way

The embryos in the Bernard Price Institute collection of Karoo vertebrates at the Evolutionary Studies Institute of the University of the Witwatersrand.
Photo: Ilse van der Merwe, NSCF

Dinosaur Eggs with Embryos

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Eggs with embryos belonging to the southern African dinosaur Massospondylus were discovered in 1978 from a road cut-away in the Golden Gate National Park in the Free State.

A clutch of six eggs was removed but these were surrounded by a rock matrix. The scientists believed that attempting to remove the eggs would damage them. Xrays revealed the presence of embryos, but these remained hidden until 2005 when these eggs were carefully partially prepared out of the rock. Once the detail of the structure of the embryos was revealed, scientists were able to improve their understanding about the development of this remarkable dinosaur.

These dinosaurs lived in the early Jurassic, between 200 and 183 million years ago. measured around 4 metres in length and weighing around 1000 kilogrammes, though some sources estimate its length as high as 6 metres. It had a slender body, a long neck, and a relatively small head.

Most recently, Wits scientists (Chapelle et al., 2021) utilised the high-powered and intense energy of the European Synchrotron Radiation Facility (ESRF), located at Grenoble in France to unscramble the embryonic development of dinosaurs. These embryos are in the Bernard Price Institute collection of Karoo vertebrates at the Evolutionary Studies Institute (ESI) of the University of the Witwatersrand.

Basic Water Cycle

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The natural water cycle is powered by the sun's energy and by gravity. The sun heats the Earth's surface water, making it evaporate. Gravity makes the moisture fall back to Earth. There are four main stages in the water cycle:

Evaporation: when the heat from the sun causes water on the surfaces of oceans, lakes, streams, ice and soils to evaporate and turn into water vapour, a gas, which then rises and mixes with the air. Evaporation is an important purification stage. When water evaporates into water vapour, the salts are left behind.

Condensation: when water vapour in the air cools down and turns into tiny water droplets – often forming around dust particles in the air. This can be caused when the air moves to a higher and colder altitude or due to a change in pressure. Water droplets float together to form clouds.

Precipitation: when water (in the form of rain, snow, hail or sleet) falls from the sky. The water droplets in the clouds combine to from larger droplets until they are heavy enough to fall as rain. If the conditions are cold enough, they can freeze into solid hail during their descent. Snow is formed when water vapour freezes directly onto ice particles forming delicate crystals which float to the ground.

Collection: when water that falls as rain, snow, hail or sleet, collects in the oceans, rivers, lakes, streams. Much of the water will soak into the ground and will collect as underground water before emerging in rivers.

Building Structure

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This is the exciting stage of actually constructing the new building. The plans for the building would have been drawn up by an architect with the help of planners and engineers and approved by various authorities. The contractors will have been selected and work is underway. The work involves many machines including cranes, concrete mixers and pumps, excavator and trucks, and also scaffolding.

Construction:
The construction team will excavate the site; create the foundation of the building; erect the support framework (skeleton, also called the superstructure) around which the building will be built (usually reinforced concrete and/or steel sections); build the structure, one floor at a time (out of brick or other materials) and install pipes and cables for plumbing and electrical services and IT networks.

Finishing:
Finishing refers to the non-structural elements that are applied to the exterior and interior of the building. It involves covering the brick or concrete of the building with a finish such as plaster, painting the walls, installing any external cladding and windows, installing internal walls (sound-proof insulated panels), adding electrical outlets, installing plumbing fixtures (toilets and sinks) and laying down the flooring (tiles or carpets). Once the building is finished, and all the safety checks are passed, the tenants can start using the building.

Mountain

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Mountains are rocky geological features on a landscape that are created through the tectonic movement of the surface of the earth or even through volcanic activity.

Tectonic formations occur when parts of the earth’s crust press up against each other and raise the surface into a mountain. Volcanic activity can form peaks when molten rock (magma) from the earth’s mantle erupts and pushes through the earth’s crust. The magma then piles up to create a mountain, usually conical in shape.

The landscape is then shaped over millions of years by the flow of ice and water that cut through the mountains forming ‘U’ and ‘V’-shaped valleys respectively.

Studying the structure of mountains and their rock types can tell us much about the history of the formation of the earth.

Groups of people who live in mountainous areas may adapt to the different weather conditions and altitudes. As you climb up a mountain, the air becomes thinner. Some peoples, who have lived at high altitude for many generations, have physically adapted to have expanded lungs so they can breathe easier even with the lower oxygen levels.

The embryos in the Bernard Price Institute collection of Karoo vertebrates at the Evolutionary Studies Institute of the University of the Witwatersrand.
Photo: Ilse van der Merwe, NSCF

Dinosaur Eggs with Embryos

---

Eggs with embryos belonging to the southern African dinosaur Massospondylus were discovered in 1978 from a road cut-away in the Golden Gate National Park in the Free State.

A clutch of six eggs was removed but these were surrounded by a rock matrix. The scientists believed that attempting to remove the eggs would damage them. Xrays revealed the presence of embryos, but these remained hidden until 2005 when these eggs were carefully partially prepared out of the rock. Once the detail of the structure of the embryos was revealed, scientists were able to improve their understanding about the development of this remarkable dinosaur.

These dinosaurs lived in the early Jurassic, between 200 and 183 million years ago. measured around 4 metres in length and weighing around 1000 kilogrammes, though some sources estimate its length as high as 6 metres. It had a slender body, a long neck, and a relatively small head.

Most recently, Wits scientists (Chapelle et al., 2021) utilised the high-powered and intense energy of the European Synchrotron Radiation Facility (ESRF), located at Grenoble in France to unscramble the embryonic development of dinosaurs. These embryos are in the Bernard Price Institute collection of Karoo vertebrates at the Evolutionary Studies Institute (ESI) of the University of the Witwatersrand.

Building Structure

---

This is the exciting stage of actually constructing the new building. The plans for the building would have been drawn up by an architect with the help of planners and engineers and approved by various authorities. The contractors will have been selected and work is underway. The work involves many machines including cranes, concrete mixers and pumps, excavator and trucks, and also scaffolding.

Construction:
The construction team will excavate the site; create the foundation of the building; erect the support framework (skeleton, also called the superstructure) around which the building will be built (usually reinforced concrete and/or steel sections); build the structure, one floor at a time (out of brick or other materials) and install pipes and cables for plumbing and electrical services and IT networks.

Finishing:
Finishing refers to the non-structural elements that are applied to the exterior and interior of the building. It involves covering the brick or concrete of the building with a finish such as plaster, painting the walls, installing any external cladding and windows, installing internal walls (sound-proof insulated panels), adding electrical outlets, installing plumbing fixtures (toilets and sinks) and laying down the flooring (tiles or carpets). Once the building is finished, and all the safety checks are passed, the tenants can start using the building.

Plants and Animals on Earth: - Many different plants and animals - Inter-dependence - Animal types

Animal Skeletons: - Skeletons of vertebrates - Movement

Food Chains: - Food and feeding

Life Cycles: - Growth and development

The Eye

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The eye is a fused two-piece unit, The anterior (front) segment is made up of the cornea, iris and lens. The cornea is transparent and more curved, and is linked to the larger posterior segment, composed of the vitreous, retina, choroid and the outer white shell called the sclera. The cornea is typically about 12 mm in diameter, and 0.5 mm thick near its centre. The posterior (rear) chamber constitutes the remaining five-sixths; its diameter is typically about 24 mm. The iris is the circular pigmented area surrounding the centre of the eye, the pupil, which appears to be black. The size of the pupil, which controls the amount of light entering the eye, is adjusted by the iris' dilator and sphincter muscles.

Light energy enters the eye through the cornea, then the pupil and then the lens, before falling on the light-sensitive cells of the retina (photoreceptor cones and rods) that generate electrical signals that are transmitted to the brain by the optic nerve and interpreted as sight and vision. The lens shape is changed for near focus (accommodation) and is controlled by the ciliary muscle.

When the eye views an object far away, the rays of light entering the eye are parallel. The ciliary muscles and suspensory ligaments cause the lens to flatten. Conversely, when the object is close to the eye, the light enters at an angle and the muscles and ligaments allow the lens to fatten (convex) so the eye can focus on the close object. When the eye is unable to adjust the lens shape sufficiently, then glasses can be worn to correct the focus.

There are six extraocular muscles that control eye movements. By having two eyes, stereo vision, animals are able to judge distance to objects.

The Ear

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The ear is the organ that enables hearing and, in mammals, body balance using the vestibular system. In mammals, the ear is usually described as having three parts — the outer ear, the middle ear and the inner ear. The outer ear consists of the pinna and the ear canal. Since the outer ear is the only visible portion of the ear in most animals, the word "ear" often refers to the external part alone. The middle ear includes the tympanic cavity and the three ossicles. The inner ear sits in the bony labyrinth, and contains structures which are key to several senses: the semicircular canals, which enable balance and eye tracking when moving; the utricle and saccule, which enable balance when stationary; and the cochlea, which enables hearing. The ears of vertebrates are placed somewhat symmetrically on either side of the head, an arrangement that aids sound localisation.

The ear develops from the first pharyngeal pouch and six small swellings that develop in the early embryo called otic placodes, which are derived from ectoderm.

The ear has been adorned by earrings and other jewelry in numerous cultures for thousands of years, and has been subjected to surgical and cosmetic alterations.

The ear may be affected by disease, including infection and traumatic damage. Diseases of the ear may lead to hearing loss, tinnitus and balance disorders such as vertigo, although many of these conditions may also be affected by damage to the brain or neural pathways leading from the ear.

The Heart

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The heart is an organ that pumps blood throughout the body via the circulatory system, supplying oxygen and nutrients to muscles and tissues and removing carbon dioxide and other waste products.

The heart is a muscle, about the size of your fist, in the middle of your chest tilted slightly to the left. Each day your heart beats around 100,000 times, circulating about five litres (eight pints) of blood. Replenished blood is distributed through a network of arteries, returning through a complementary network of veins. In between are tiny capillaries with very thin walls, which allow them to exchange compounds (such as oxygen and carbon dioxide, water, nutrients and waste) with surrounding tissues. Waste products are removed from the blood in the kidneys.

The right side of the heart receives deoxygenated blood and sends it to the lungs, which remove the carbon dioxide and replenish with oxygen. The left side receives blood from the lungs and pumps it to all parts of the body. Arteries are strong and their elastic walls help keep blood pressure consistent. Veins have thinner walls than arteries.

When exercising, the heart beats faster to get oxygen and nutrients to the muscles, increasing from an idling rate of 60 beats per minute to almost 200 bpm. The heart can take strain without you being aware of it. Over a long period of time your diet can influence the condition of your blood vessels and valves of the heart. Monitoring blood pressure is essential to know the condition of your circulatory system.

Human Digestive System

---

Your digestive system turns the food you eat into nutrients, which the body uses for energy, growth and cell repair. The digestion process starts in your mouth. Biting and chewing breaks the food into pieces that are more easily digested, while saliva mixes with food to begin the process of breaking it down into a form your body can absorb and use.

The throat (pharynx) is a muscular valve that controls airflow into the lungs and directs solids and liquids towards the stomach through the oesophagus.

The oesophagus is a muscular tube extending from the throat to the stomach. The oesophagus delivers food to the stomach through a series of contractions, called peristalsis. Just before the connection to the stomach, there is a "zone of high pressure", called the lower oesophageal sphincter which prevents food from passing back into the oesophagus.

The stomach is a sac-like organ with strong muscular walls. In addition to holding the food, it's also a mixer and grinder. The stomach secretes acid and powerful enzymes that continue the process of breaking down the food. When it leaves the stomach, food is the consistency of a liquid or paste. From there, the food moves to the small intestine.

The liver filters the blood coming from the digestive tract before it passes to the rest of the body. The liver also detoxifies chemicals and metabolises drugs. The liver secretes bile via the gallbladder back to the intestines.

The pancreas plays an essential role in converting the food we eat into fuel for the body's cells. It has two main functions—the exocrine function that helps digestion, and a vital endocrine function that regulates blood sugar.

The small intestine is a 6m long tube, loosely coiled in the abdomen, made up of three segments, the duodenum, jejunum, and ileum. The small intestine continues the process of breaking down food using segmentation (bi-directional peristaltic contractions) and enzymes released by the pancreas and bile from the liver. Bile aids in the digestion of fat and eliminates waste products from the blood. The duodenum is mainly responsible for breaking down food, with the jejunum and ileum being mainly responsible for the absorption of nutrients into the bloodstream.

The final stage of the journey for solids is through the large intestine to the rectum for final discharge through the anus.

Human Nervous System

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The nervous system is a sophisticated collection of nerves and specialised cells called neurons that transmit signals between different parts of the body. It is essentially the body's electrical wiring.

The brain and spinal cord together form the central nervous system; all the other nerves in the body are the peripheral nervous system. The nerves themselves are cylindrical bundles of fibres.

The brain is the central computer of the nervous system. It receives messages from the body, processes the information, and sends signals back to tell the body how to respond. The spinal cord is the main information highway of the nervous system and connects the brain to all the nerves that help you sense the world.

The peripheral nervous system includes sensory nerves that receive information from your sensory organs (your eyes, ears, nose, tongue and skin) and motor nerves that carry information to muscles throughout your body. There are many other kinds of nerves in the peripheral nervous system that have special functions for communicating with your internal organs (e.g. heart, lungs and liver.)

Neurons send signals to other cells through thin fibres called axons, which cause chemicals known as neurotransmitters to be released at junctions called synapses. There are 86 billion neural connections in the average human brain.

Human Muscles

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Muscles are a type of soft tissue found in humans and most animals. Muscles allow us to consciously move our limbs so we can jump in the air, chew our food and perform other conscious actions. They are also responsible for many sub-conscious processes, such as keeping our hearts pumping, moving food through our guts, and even making us blush.

Our muscles need signals from our brains and energy from our food to contract and move. There are two types of muscles. Striated muscles consist of multiple fibres arranged in parallel, whereas smooth muscles have interconnected cells that form layers.

The skeletal muscles that move our body parts are striated muscles, and we actively control these with our brain. We are not able to control all the striated muscles, like those that keep our hearts pumping. These muscles work on their own without us even thinking about it.

Specific molecules within the muscle fibres, particularly actin and myosin, allow striated muscles to contract rapidly, allowing us to move. The energy for muscles comes from the food that we eat.

The contractions that smooth muscles produce tend to be more gradual than those produced by striated muscle. An example is the slow and controlled movement of food through the digestive system.

Although the pathways that regulate contraction in striated and smooth muscles are very different, calcium is the common key molecular messenger in the process.

Striated muscles receive their triggers from the brain via motor neurons, whereas smooth muscle cells are activated by neuronal signalling or by hormones. This results in calcium rushing into the muscle, activating the actin and myosin and causing the muscle to contract.

Some smooth muscles are in a permanent state of contraction, and the muscles that line our blood vessels are in this category. A constant supply of calcium allows these muscles to regulate blood flow. For example, when the muscles that line the blood vessels in our face relax, we blush.

Human Skeleton

---

The skeletal system includes all the bones and joints in the body. Each bone is a complex living organ made up of many cells, protein fibres, and minerals. The skeleton provides support and protection (skull and ribs) for the soft organs that make up the rest of the body. The bones have attachment points for muscles and tendons to allow movements at the joints. The red bone marrow produces new blood cells inside of our bones. Bones act as the body’s warehouse.

The skeletal system in an adult body is made up of 206 individual bones arranged into two major divisions:
• The axial skeleton (80 bones) runs along the body’s vertical axis and includes the skull, ribs, sternum, and vertebral column.
• The appendicular skeleton (126 bones) makes up the limbs, the shoulder, and pelvic girdles.

The skeleton makes up about 30-40% of an adult’s body mass and consists of non-living bone matrix and many tiny bone cells. Roughly half of the bone mass is water, while the other half is collagen protein and solid crystals of calcium carbonate and calcium phosphate.

Living bone cells are found on the surfaces of bones and in small cavities inside the bone matrix. Although these cells make up very little of the total bone mass, they are essential for bone growth and repair during daily wear and injury.

The bone matrix is our calcium bank, storing and releasing calcium ions into the blood as needed for the proper function of the nervous and muscular systems. Red bone marrow is found in the hollow space inside of bones known as the medullary cavity and produces red and white blood cells in a process known as haematopoiesis. Red bone marrow also stores iron used to form haemoglobin in red blood cells.

Five Basic Senses

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Humans have five basic senses: touch, sight, hearing, smell and taste. The sensory organs (skin, eyes, ears, nose and tongue) send information to the brain to help us perceive the world around us.

For touch, several distinct sensations in the skin are communicated to the brain through specialized neurons.

For sight, light passes through the lens of an eye. It is focussed onto the retina where photoreceptors called rods (for black and white) and cones (for colour) convert the information into electrical impulses sent to the brain. The iris (coloured part of the eye) controls how much light enters the eye.

For hearing, sound waves pass from the outer ear, through the auditory canal and onto the eardrum. In the middle ear, delicate bones transfer the vibrations to fine hairs in the inner ear, which produce electrical signals that the brain decodes as sound.

For smell, there are millions of nerve endings in the olfactory cleft in the roof of the nasal cavity, that transmit complex smell information directly to the brain. The number of unique smell combinations is almost infinite.

For taste, receptors around our tongue, the roof of the mouth and throat detect the four primary tastes: salty, sweet, sour and bitter. Recently a fifth taste, umami (or savoury) has been added.

The Eye

---

The eye is a fused two-piece unit, The anterior (front) segment is made up of the cornea, iris and lens. The cornea is transparent and more curved, and is linked to the larger posterior segment, composed of the vitreous, retina, choroid and the outer white shell called the sclera. The cornea is typically about 12 mm in diameter, and 0.5 mm thick near its centre. The posterior (rear) chamber constitutes the remaining five-sixths; its diameter is typically about 24 mm. The iris is the circular pigmented area surrounding the centre of the eye, the pupil, which appears to be black. The size of the pupil, which controls the amount of light entering the eye, is adjusted by the iris' dilator and sphincter muscles.

Light energy enters the eye through the cornea, then the pupil and then the lens, before falling on the light-sensitive cells of the retina (photoreceptor cones and rods) that generate electrical signals that are transmitted to the brain by the optic nerve and interpreted as sight and vision. The lens shape is changed for near focus (accommodation) and is controlled by the ciliary muscle.

When the eye views an object far away, the rays of light entering the eye are parallel. The ciliary muscles and suspensory ligaments cause the lens to flatten. Conversely, when the object is close to the eye, the light enters at an angle and the muscles and ligaments allow the lens to fatten (convex) so the eye can focus on the close object. When the eye is unable to adjust the lens shape sufficiently, then glasses can be worn to correct the focus.

There are six extraocular muscles that control eye movements. By having two eyes, stereo vision, animals are able to judge distance to objects.

The Ear

---

The ear is the organ that enables hearing and, in mammals, body balance using the vestibular system. In mammals, the ear is usually described as having three parts — the outer ear, the middle ear and the inner ear. The outer ear consists of the pinna and the ear canal. Since the outer ear is the only visible portion of the ear in most animals, the word "ear" often refers to the external part alone. The middle ear includes the tympanic cavity and the three ossicles. The inner ear sits in the bony labyrinth, and contains structures which are key to several senses: the semicircular canals, which enable balance and eye tracking when moving; the utricle and saccule, which enable balance when stationary; and the cochlea, which enables hearing. The ears of vertebrates are placed somewhat symmetrically on either side of the head, an arrangement that aids sound localisation.

The ear develops from the first pharyngeal pouch and six small swellings that develop in the early embryo called otic placodes, which are derived from ectoderm.

The ear has been adorned by earrings and other jewelry in numerous cultures for thousands of years, and has been subjected to surgical and cosmetic alterations.

The ear may be affected by disease, including infection and traumatic damage. Diseases of the ear may lead to hearing loss, tinnitus and balance disorders such as vertigo, although many of these conditions may also be affected by damage to the brain or neural pathways leading from the ear.

The Heart

---

The heart is an organ that pumps blood throughout the body via the circulatory system, supplying oxygen and nutrients to muscles and tissues and removing carbon dioxide and other waste products.

The heart is a muscle, about the size of your fist, in the middle of your chest tilted slightly to the left. Each day your heart beats around 100,000 times, circulating about five litres (eight pints) of blood. Replenished blood is distributed through a network of arteries, returning through a complementary network of veins. In between are tiny capillaries with very thin walls, which allow them to exchange compounds (such as oxygen and carbon dioxide, water, nutrients and waste) with surrounding tissues. Waste products are removed from the blood in the kidneys.

The right side of the heart receives deoxygenated blood and sends it to the lungs, which remove the carbon dioxide and replenish with oxygen. The left side receives blood from the lungs and pumps it to all parts of the body. Arteries are strong and their elastic walls help keep blood pressure consistent. Veins have thinner walls than arteries.

When exercising, the heart beats faster to get oxygen and nutrients to the muscles, increasing from an idling rate of 60 beats per minute to almost 200 bpm. The heart can take strain without you being aware of it. Over a long period of time your diet can influence the condition of your blood vessels and valves of the heart. Monitoring blood pressure is essential to know the condition of your circulatory system.

Human Digestive System

---

Your digestive system turns the food you eat into nutrients, which the body uses for energy, growth and cell repair. The digestion process starts in your mouth. Biting and chewing breaks the food into pieces that are more easily digested, while saliva mixes with food to begin the process of breaking it down into a form your body can absorb and use.

The throat (pharynx) is a muscular valve that controls airflow into the lungs and directs solids and liquids towards the stomach through the oesophagus.

The oesophagus is a muscular tube extending from the throat to the stomach. The oesophagus delivers food to the stomach through a series of contractions, called peristalsis. Just before the connection to the stomach, there is a "zone of high pressure", called the lower oesophageal sphincter which prevents food from passing back into the oesophagus.

The stomach is a sac-like organ with strong muscular walls. In addition to holding the food, it's also a mixer and grinder. The stomach secretes acid and powerful enzymes that continue the process of breaking down the food. When it leaves the stomach, food is the consistency of a liquid or paste. From there, the food moves to the small intestine.

The liver filters the blood coming from the digestive tract before it passes to the rest of the body. The liver also detoxifies chemicals and metabolises drugs. The liver secretes bile via the gallbladder back to the intestines.

The pancreas plays an essential role in converting the food we eat into fuel for the body's cells. It has two main functions—the exocrine function that helps digestion, and a vital endocrine function that regulates blood sugar.

The small intestine is a 6m long tube, loosely coiled in the abdomen, made up of three segments, the duodenum, jejunum, and ileum. The small intestine continues the process of breaking down food using segmentation (bi-directional peristaltic contractions) and enzymes released by the pancreas and bile from the liver. Bile aids in the digestion of fat and eliminates waste products from the blood. The duodenum is mainly responsible for breaking down food, with the jejunum and ileum being mainly responsible for the absorption of nutrients into the bloodstream.

The final stage of the journey for solids is through the large intestine to the rectum for final discharge through the anus.

Human Nervous System

---

The nervous system is a sophisticated collection of nerves and specialised cells called neurons that transmit signals between different parts of the body. It is essentially the body's electrical wiring.

The brain and spinal cord together form the central nervous system; all the other nerves in the body are the peripheral nervous system. The nerves themselves are cylindrical bundles of fibres.

The brain is the central computer of the nervous system. It receives messages from the body, processes the information, and sends signals back to tell the body how to respond. The spinal cord is the main information highway of the nervous system and connects the brain to all the nerves that help you sense the world.

The peripheral nervous system includes sensory nerves that receive information from your sensory organs (your eyes, ears, nose, tongue and skin) and motor nerves that carry information to muscles throughout your body. There are many other kinds of nerves in the peripheral nervous system that have special functions for communicating with your internal organs (e.g. heart, lungs and liver.)

Neurons send signals to other cells through thin fibres called axons, which cause chemicals known as neurotransmitters to be released at junctions called synapses. There are 86 billion neural connections in the average human brain.

Human Muscles

---

Muscles are a type of soft tissue found in humans and most animals. Muscles allow us to consciously move our limbs so we can jump in the air, chew our food and perform other conscious actions. They are also responsible for many sub-conscious processes, such as keeping our hearts pumping, moving food through our guts, and even making us blush.

Our muscles need signals from our brains and energy from our food to contract and move. There are two types of muscles. Striated muscles consist of multiple fibres arranged in parallel, whereas smooth muscles have interconnected cells that form layers.

The skeletal muscles that move our body parts are striated muscles, and we actively control these with our brain. We are not able to control all the striated muscles, like those that keep our hearts pumping. These muscles work on their own without us even thinking about it.

Specific molecules within the muscle fibres, particularly actin and myosin, allow striated muscles to contract rapidly, allowing us to move. The energy for muscles comes from the food that we eat.

The contractions that smooth muscles produce tend to be more gradual than those produced by striated muscle. An example is the slow and controlled movement of food through the digestive system.

Although the pathways that regulate contraction in striated and smooth muscles are very different, calcium is the common key molecular messenger in the process.

Striated muscles receive their triggers from the brain via motor neurons, whereas smooth muscle cells are activated by neuronal signalling or by hormones. This results in calcium rushing into the muscle, activating the actin and myosin and causing the muscle to contract.

Some smooth muscles are in a permanent state of contraction, and the muscles that line our blood vessels are in this category. A constant supply of calcium allows these muscles to regulate blood flow. For example, when the muscles that line the blood vessels in our face relax, we blush.

Human Skeleton

---

The skeletal system includes all the bones and joints in the body. Each bone is a complex living organ made up of many cells, protein fibres, and minerals. The skeleton provides support and protection (skull and ribs) for the soft organs that make up the rest of the body. The bones have attachment points for muscles and tendons to allow movements at the joints. The red bone marrow produces new blood cells inside of our bones. Bones act as the body’s warehouse.

The skeletal system in an adult body is made up of 206 individual bones arranged into two major divisions:
• The axial skeleton (80 bones) runs along the body’s vertical axis and includes the skull, ribs, sternum, and vertebral column.
• The appendicular skeleton (126 bones) makes up the limbs, the shoulder, and pelvic girdles.

The skeleton makes up about 30-40% of an adult’s body mass and consists of non-living bone matrix and many tiny bone cells. Roughly half of the bone mass is water, while the other half is collagen protein and solid crystals of calcium carbonate and calcium phosphate.

Living bone cells are found on the surfaces of bones and in small cavities inside the bone matrix. Although these cells make up very little of the total bone mass, they are essential for bone growth and repair during daily wear and injury.

The bone matrix is our calcium bank, storing and releasing calcium ions into the blood as needed for the proper function of the nervous and muscular systems. Red bone marrow is found in the hollow space inside of bones known as the medullary cavity and produces red and white blood cells in a process known as haematopoiesis. Red bone marrow also stores iron used to form haemoglobin in red blood cells.

Five Basic Senses

---

Humans have five basic senses: touch, sight, hearing, smell and taste. The sensory organs (skin, eyes, ears, nose and tongue) send information to the brain to help us perceive the world around us.

For touch, several distinct sensations in the skin are communicated to the brain through specialized neurons.

For sight, light passes through the lens of an eye. It is focussed onto the retina where photoreceptors called rods (for black and white) and cones (for colour) convert the information into electrical impulses sent to the brain. The iris (coloured part of the eye) controls how much light enters the eye.

For hearing, sound waves pass from the outer ear, through the auditory canal and onto the eardrum. In the middle ear, delicate bones transfer the vibrations to fine hairs in the inner ear, which produce electrical signals that the brain decodes as sound.

For smell, there are millions of nerve endings in the olfactory cleft in the roof of the nasal cavity, that transmit complex smell information directly to the brain. The number of unique smell combinations is almost infinite.

For taste, receptors around our tongue, the roof of the mouth and throat detect the four primary tastes: salty, sweet, sour and bitter. Recently a fifth taste, umami (or savoury) has been added.

Lungs

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Human lungs are remarkable organs responsible for the crucial task of breathing, which provides oxygen to the body's cells and removes carbon dioxide, a waste product of metabolism. Each person has two lungs, situated in the chest cavity on either side of the heart. The lungs are spongy in texture and pinkish in color, resembling two large air-filled balloons.

The lungs are divided into sections called lobes – three on the right lung and two on the left. Inside the lungs are a vast network of airways, including the trachea (windpipe), bronchi, and bronchioles, which branch out like tree limbs and end in small air sacs called alveoli. It is within these alveoli that the exchange of gases occurs: oxygen from the air enters the bloodstream, while carbon dioxide from the bloodstream exits the body when we exhale.

The process of breathing, also known as respiration, is controlled by the respiratory system, which includes the lungs, airways, and muscles involved in breathing. When we inhale, the diaphragm – a dome-shaped muscle beneath the lungs – contracts and moves downward, creating space for the lungs to expand. This allows air to rush into the lungs. When we exhale, the diaphragm relaxes, and the lungs recoil, pushing air out of the body.

Human lungs are essential for survival, as they enable the body to receive the oxygen it needs to function properly. Maintaining lung health is crucial for overall well-being, and practices such as regular exercise, avoiding smoking and pollution, and maintaining a healthy diet can help support lung function.

Kidneys

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Human kidneys are vital organs responsible for filtering waste products and excess fluids from the bloodstream to produce urine. Each person has two kidneys, located on either side of the spine, just below the rib cage. The kidneys are bean-shaped organs, reddish-brown in color, and about the size of a fist.

The main function of the kidneys is to remove waste products, such as urea and creatinine, from the blood and excrete them in the form of urine. Additionally, the kidneys regulate the body's fluid balance, electrolyte levels, and blood pressure by adjusting the concentration and volume of urine produced.

Inside each kidney are tiny structures called nephrons, which are responsible for the filtration and purification of blood. Each nephron consists of a filtering unit called the glomerulus, surrounded by a tubule. As blood passes through the glomerulus, waste products and excess fluids are filtered out and collected in the tubule, while essential substances such as water, electrolytes, and glucose are reabsorbed back into the bloodstream.

The kidneys also play a crucial role in the production of hormones that regulate various bodily functions. For example, they produce erythropoietin, which stimulates the production of red blood cells, and renin, which helps regulate blood pressure.

Maintaining kidney health is essential for overall well-being, as kidney dysfunction can lead to serious health problems, including kidney disease, kidney stones, and electrolyte imbalances. Practices such as staying hydrated, maintaining a healthy diet, and avoiding excessive consumption of alcohol and certain medications can help support kidney function..

Liver

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The human liver is a vital organ with multiple functions essential for maintaining overall health and well-being. It is the largest internal organ in the body and is located in the upper right side of the abdomen, just below the diaphragm. The liver is reddish-brown in color and has a soft, spongy texture.

One of the liver's primary functions is to filter and detoxify blood coming from the digestive tract before it circulates throughout the rest of the body. It removes harmful substances such as toxins, drugs, and alcohol from the bloodstream, converting them into less harmful compounds that can be excreted from the body.

The liver also plays a crucial role in metabolism, the process by which the body converts food into energy. It helps regulate blood sugar levels by storing glucose as glycogen and releasing it into the bloodstream when needed. Additionally, the liver synthesizes proteins necessary for blood clotting, immune function, and transport of nutrients throughout the body.

Another important function of the liver is the production of bile, a greenish-yellow fluid that helps digest fats in the small intestine. Bile is produced in the liver and stored in the gallbladder until it is needed for digestion. The liver continuously produces bile to aid in the digestion and absorption of fats from the diet.

Maintaining liver health is crucial for overall well-being, as liver dysfunction can lead to serious health problems, including liver disease, hepatitis, and liver cancer. Practices such as maintaining a healthy diet, limiting alcohol consumption, and avoiding exposure to toxins can help support liver function and prevent liver-related complications.

Fungi

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Fungi are all around us, in the soil, our bodies and the air, but are often too small to be seen with the naked eye. There are 120,000 classified types of fungi. Scientists estimate that there are 2.2 – 3.8 million species in total, including mushrooms, yeast, lichens, rust, and mold.

Fungi are non-motile, heterotrophic (no chlorophyll), unicellular (yeast) or filamentous (fungus), reproduce by means of spores, consist of long thread-like structures known as hyphae that form a mesh-like structure called mycelium.

Some play an important role in the decomposition of organic material and nutrient cycling in nature, while others form symbiotic relationships with plants. Others are plant or animal pathogens or endophytes (living inside a plant). They also serve as a food source for a large variety of organisms, including humans.

They occur in most habitats from the Arctic to Antarctica, from high mountain tops to desert sand. Some even lives in marine and fresh water environments. More than 90% of the estimated 3.8 million fungi in the world are currently unknown to science.

Did you know?
1. A fungus lives in symbioses with algae and this beneficial lifeform is called a lichen.
2. Fungi are in a kingdom of their own but are closer to animals than plants.
3. They have chemicals in their cell walls shared with lobsters and crabs.
4. There is evidence to suggest that yeasts - a type of fungus - were being used to produce the alcoholic drink mead as long ago as 9,000 years ago.
5. Products made from fungi can be used as replacements for polystyrene foam, leather and building materials.
6. DNA studies show that there are thousands of different fungi in a single sample of soil, many of which are unknown and hidden.
7. They are 2-10µm in size.
8. A huge underground fungus that is one of the largest living organisms on the planet. It spanned at least 0.37 square kilometres .It was estimated in 1980 to be at least 1500 years old and weighed at least 100,000 kilograms.
9. Fungi affects every part of your life, what you eat, what you wear, what you do and your mood.
10. Mycorrhizal fungus forms an essential symbiotic relationship with plant roots. Mycorrhizal fungi help tree and shrub roots find water and nutrients. In return, the roots give the fungi carbon, carbohydrates, and other nutrients.
11. Mushrooms and other fungi release an incredible amount of spores into the atmosphere every year, and contributing up to 50 million tonnes of particulates.

Telescope

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Telescopes stand as humanity's windows to the cosmos, offering unparalleled glimpses into the vast expanse of space and the wonders it holds. This educational journey delves into the realms of optics, astronomy, celestial objects, space exploration, and the rich history of telescopes, illuminating the fascinating intersection of science, technology, and human curiosity.

At the heart of the telescope's marvel lies the science of optics, which explores the behaviour of light and its interaction with lenses and mirrors. Telescopes harness the principles of optics to collect and focus light from distant celestial objects, enabling astronomers to observe and study them in detail. Through the careful design and construction of lenses, mirrors, and other optical components, telescopes magnify faint and distant objects, unveiling the secrets of the universe.

Astronomy, the study of celestial objects and phenomena beyond Earth's atmosphere, is intrinsically linked to the telescope's capabilities. Telescopes serve as indispensable tools for astronomers, allowing them to explore the cosmos across a broad range of wavelengths, from visible light to radio waves, X-rays, and beyond. By observing stars, galaxies, nebulae, and other cosmic entities, astronomers unravel the mysteries of the universe, probing its origins, evolution, and ultimate fate.

The history of telescopes is a testament to human ingenuity and the quest for understanding the cosmos. From the humble beginnings of early optical devices, such as the refracting telescope invented by Dutch spectacle maker Hans Lippershey in the early 17th century, to the cutting-edge technologies of modern observatories like the Hubble Space Telescope, telescopes have undergone remarkable advancements over the centuries. Each milestone in telescope development has expanded our view of the universe and revolutionized our understanding of the cosmos.

Telescopes have played pivotal roles in space exploration, providing vital data and imagery for missions to study planets, moons, asteroids, comets, and other celestial bodies. Space telescopes, like the Hubble Space Telescope and the James Webb Space Telescope, offer unparalleled views of the universe from beyond Earth's atmosphere, free from the distorting effects of the atmosphere.

Mercury

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Mercury, the closest planet to the Sun, is a fascinating world of extremes. It's the smallest planet in our solar system, with a diameter just a bit larger than Earth's Moon. Despite its diminutive size, Mercury is a fiery planet, experiencing temperatures that range from scorching hot to freezing cold. During the day, when Mercury faces the Sun, temperatures can soar up to a blistering 800 degrees Fahrenheit (430 degrees Celsius). However, at night, when Mercury turns away from the Sun, temperatures plummet to a bone-chilling minus 290 degrees Fahrenheit (minus 180 degrees Celsius).

Mercury is a rocky planet with a heavily cratered surface, resembling the surface of Earth's Moon. Its surface features include vast plains, towering cliffs, and deep craters formed by impacts from asteroids and comets. The planet's lack of atmosphere means there is no protection from these impacts or from the Sun's intense radiation.

Despite its proximity to the Sun, Mercury is not the hottest planet in our solar system. That title goes to Venus, the second planet from the Sun. However, Mercury does have the greatest temperature variation between its day and night sides, making it one of the most extreme environments in our solar system.

Venus

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Venus, often called Earth's "twin" due to its similar size and composition, is a mysterious and inhospitable world. It is the second planet from the Sun and is often referred to as the "morning star" or the "evening star" because it is one of the brightest objects in the night sky. Despite its beauty when viewed from Earth, Venus is a hostile planet with surface temperatures hot enough to melt lead.

The surface of Venus is shrouded in thick clouds of sulfuric acid, making it impossible to see the planet's surface with the naked eye. These clouds trap heat from the Sun, creating a runaway greenhouse effect that has caused Venus to become the hottest planet in our solar system, even hotter than Mercury.

Beneath its toxic atmosphere, Venus has a rocky surface with vast plains, towering mountains, and deep valleys. It is home to numerous volcanoes, including the massive Maxwell Montes, which is the highest mountain on Venus. The planet's surface is littered with volcanic features, indicating a history of volcanic activity.

Despite its extreme conditions, scientists are intrigued by Venus and continue to study its atmosphere and surface using spacecraft and telescopes. Understanding Venus could provide valuable insights into the processes that shape rocky planets and help scientists better understand the potential for life beyond Earth.

Earth

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Earth, our home planet, is a unique and vibrant world teeming with life. It is the third planet from the Sun and the only planet in our solar system known to support life. Earth's surface is covered in vast oceans, lush forests, towering mountains, and sprawling deserts, creating a diverse and dynamic environment.

One of the most remarkable features of Earth is its atmosphere, which is composed primarily of nitrogen and oxygen. This atmosphere acts as a protective shield, filtering out harmful solar radiation and regulating the planet's temperature. Earth's atmosphere also plays a crucial role in the water cycle, weather patterns, and climate regulation.

The surface of Earth is divided into several major landmasses, including continents and islands, which are surrounded by vast oceans. These landmasses are constantly shifting and changing due to processes like plate tectonics and erosion, shaping the planet's landscape over millions of years.

Earth is also home to a staggering array of life forms, from microscopic bacteria to towering trees and majestic animals. The diversity of life on Earth is unparalleled, with millions of species inhabiting every corner of the planet, from the depths of the ocean to the highest mountains.

In addition to its natural beauty and biodiversity, Earth is also unique in its ability to sustain life. The presence of liquid water, moderate temperatures, and a stable atmosphere make Earth the perfect habitat for a wide variety of organisms, including humans. Protecting and preserving Earth's delicate balance is essential for the continued survival of life on our planet.

The Moon

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The Moon, Earth's only natural satellite, is a fascinating and mysterious world that has captivated humans for thousands of years. It orbits around Earth at a distance of about 238,855 miles (384,400 kilometers) and is about one-quarter the size of Earth. The Moon has a rocky surface covered in craters, mountains, and plains, with no atmosphere to protect it from meteoroids and solar radiation.

One of the most striking features of the Moon is its phases, which change as it orbits around Earth. These phases, from a full moon to a new moon and back again, are caused by the relative positions of the Moon, Earth, and Sun. The Moon's gravity also affects Earth's tides, causing them to rise and fall in a predictable pattern.

The Moon has played a crucial role in human history and culture, inspiring myths, legends, and scientific inquiry. It has been the target of numerous spacecraft and missions, including the Apollo missions, which brought humans to the lunar surface for the first time. Today, the Moon continues to be a focus of scientific research and exploration, with plans for future missions to return humans to the lunar surface and establish a permanent presence there.

Mars

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Mars, often called the "Red Planet" due to its rusty hue, is a cold and barren world with a fascinating history. It is the fourth planet from the Sun and is about half the size of Earth. Mars has intrigued scientists for centuries with its potential for harboring life and its similarities to Earth.

The surface of Mars is covered in reddish-brown soil and is dotted with impact craters, volcanoes, and vast plains. One of the most prominent features of Mars is Olympus Mons, the largest volcano in the solar system, which stands nearly three times taller than Mount Everest. Mars also has a massive canyon system called Valles Marineris, which stretches for over 2,500 miles (4,000 kilometers) and is deeper than the Grand Canyon.

Despite its barren appearance, Mars has captured the imagination of scientists and explorers alike. Evidence from spacecraft and rovers suggests that Mars was once a warmer and wetter planet with rivers, lakes, and possibly even oceans. Scientists continue to search for signs of past or present life on Mars, studying its geology, atmosphere, and climate to unravel the planet's mysteries.

In recent years, Mars has become a focus of human exploration, with numerous missions planned to study the planet and prepare for future human missions. NASA's Perseverance rover, launched in 2020, is currently exploring the surface of Mars, searching for signs of ancient microbial life and collecting samples for return to Earth. The exploration of Mars holds the promise of answering fundamental questions about the potential for life beyond Earth and the future of human space exploration.

Jupiter

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Jupiter, the largest planet in our solar system, is a gas giant with a mesmerizing appearance and a host of fascinating features. It is the fifth planet from the Sun and is more than twice as massive as all the other planets combined. Jupiter's massive size and strong gravitational pull make it a dominant force in the solar system, influencing the orbits of nearby objects and protecting the inner planets from potential impacts.

One of the most striking features of Jupiter is its colorful bands of clouds, which are made up of ammonia crystals and other compounds. These bands of clouds swirl around the planet, creating mesmerizing patterns and storms that can last for centuries. The most famous of these storms is the Great Red Spot, a massive storm system that has been raging for over 300 years and is larger than Earth itself.

Beneath its thick atmosphere, Jupiter has a core made of rock and metal surrounded by layers of hydrogen and helium gas. Despite its massive size, Jupiter has no solid surface, so if you were to try to land on the planet, you would simply fall through its atmosphere until you reached its core.

Jupiter is also home to a diverse array of moons, with over 70 known moons orbiting the planet. The four largest moons – Io, Europa, Ganymede, and Callisto – are known as the Galilean moons and were discovered by the astronomer Galileo Galilei in 1610. These moons are each unique worlds with their own geology and atmosphere, and they continue to fascinate scientists with their potential for harboring life.

Saturn

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Saturn, known for its majestic rings, is the sixth planet from the Sun and the second largest in our solar system. It is a gas giant like Jupiter, composed mostly of hydrogen and helium, with a small rocky core at its center. Saturn's most distinctive feature is its rings, which are made up of billions of icy particles ranging in size from tiny grains to large chunks. These rings extend thousands of kilometers from the planet's surface and are visible even from Earth with a small telescope.

Beneath its rings, Saturn has a thick atmosphere with colorful bands of clouds, similar to Jupiter. The planet's atmosphere is primarily composed of hydrogen and helium, with traces of other gases like methane and ammonia. Saturn's atmosphere is also home to powerful storms, including a hexagonal-shaped storm near its north pole.

Saturn has a diverse collection of moons, with over 80 known moons orbiting the planet. The largest of these moons is Titan, which is larger than the planet Mercury and is the only moon in the solar system with a dense atmosphere. Titan's atmosphere is primarily composed of nitrogen, with traces of methane and other gases, making it an intriguing target for future exploration.

In addition to Titan, Saturn's moons include Enceladus, which has geysers of water vapor erupting from its surface, and Mimas, which has a large crater resembling the "Death Star" from Star Wars. These moons, along with Saturn's rings, make it one of the most captivating objects in the night sky.

The Sun

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The Sun is the star at the centre of our Solar System. It is by far the most important source of energy for life on Earth. The interactions between the Sun and Earth drive the seasons, ocean currents, weather, climate and calendar.

The Sun is 75% hydrogen and 25% helium. It’s energy comes from the fusion of hydrogen into helium. Its diameter is about 1.39 million kilometres (864 000 miles), or 109 times that of Earth, and its mass is about 330,000 times that of Earth.

The Sun currently fuses about 600 million tons of hydrogen into helium every second, converting 4 million tons of matter into energy every second producing light and heat. It takes light just over 8 minutes to travel the 150 000 000 km (93 000 000 miles) from sun to earth. Of the approximately 1 500 W/m2 of energy that reaches earth only 1 000 W/m2 reaches the ground.

Our sun’s class and size make it a yellow dwarf star. It formed approximately 4.6 billion years ago. It accounts for about 99.86% of the total mass of our solar system. The rest flattened into an orbiting disk from which the planets formed. The sun’s gravity holds our solar system together, keeping everything from the biggest planets to the smallest particles of debris in its orbit.

Electric currents in the Sun generate a magnetic field that is carried out through the solar system by the solar wind—a stream of electrically charged gas blowing outward from the Sun in all directions.

There are billions of stars like our Sun in just our Milky Way galaxy alone.

Uranus

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Uranus, the seventh planet from the Sun, is an ice giant with a mysterious and enigmatic atmosphere. It is the third largest planet in our solar system and is tilted on its side, with its axis of rotation nearly parallel to its orbit around the Sun. This unique orientation gives Uranus its distinctive appearance and causes extreme seasonal variations as it orbits the Sun.

Uranus has a thick atmosphere composed primarily of hydrogen and helium, with traces of methane that give it a blue-green color. The planet's atmosphere is marked by high-speed winds that can reach speeds of up to 560 miles per hour (900 kilometers per hour). Uranus also has a system of faint rings and a collection of moons, the largest of which is named Titania.

Despite its unique features, Uranus is one of the least explored planets in our solar system, with only one spacecraft – Voyager 2 – having visited the planet in 1986. The limited data collected by Voyager 2 has left many questions unanswered, including the origin of Uranus' unusual tilt and the composition of its atmosphere. Future missions to Uranus could provide valuable insights into the history and evolution of our solar system.

Neptune

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Neptune, the eighth and farthest planet from the Sun, is a frigid and distant world with a dynamic and turbulent atmosphere. It is the fourth largest planet in our solar system and is composed primarily of hydrogen and helium, with traces of methane that give it a blue color. Neptune's atmosphere is marked by powerful storms, including the Great Dark Spot – a massive storm system similar to Jupiter's Great Red Spot.

Neptune has a system of faint rings and a collection of moons, the largest of which is named Triton. Triton is unique among Neptune's moons because it orbits the planet in a retrograde direction, opposite to the planet's rotation. Triton is also one of the coldest objects in our solar system, with surface temperatures that can plunge to minus 391 degrees Fahrenheit (minus 235 degrees Celsius).

Despite its remote location, Neptune has been visited by only one spacecraft – Voyager 2 – which flew by the planet in 1989. Voyager 2 provided valuable data about Neptune's atmosphere, rings, and moons, but many questions remain unanswered. Future missions to Neptune could provide insights into the planet's composition, weather patterns, and geological features.

The Milky Way

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The Milky Way, our home galaxy, is a vast and majestic cosmic structure that stretches across the night sky like a shimmering river of stars. Named for its hazy appearance as seen from Earth, the Milky Way is a spiral galaxy composed of billions of stars, stellar remnants, gas, and dust, bound together by gravity.

At the heart of the Milky Way lies a dense region known as the galactic bulge, where stars are densely packed and stellar densities are highest. Surrounding the bulge is a flattened disk of stars, gas, and dust, which extends outward in a spiral pattern. Spiralling arms of stars and interstellar material spiral outwards from the central bulge, creating the iconic spiral arms that give the galaxy its distinctive appearance.

Our solar system resides in one of the Milky Way's spiral arms, known as the Orion Arm or Local Spur. From our vantage point within the galaxy, we peer outward into the vast expanse of space, observing the stars, nebulae, and other celestial objects that populate our cosmic neighbourhood.

The Milky Way is a dynamic and evolving entity, with stars orbiting the galactic centre in elliptical, circular, and spiral trajectories. Over billions of years, these stars interact with one another, forming stellar clusters, binary systems, and occasionally, catastrophic events such as supernovae and black hole mergers.

Moreover, the Milky Way is not alone in the cosmos but is part of a larger cosmic web of galaxies, clusters, and superclusters, bound together by the force of gravity. As we peer deeper into space with telescopes and observatories, we uncover the vastness of the universe and our place within it.

Studying the Milky Way provides insights into the formation, evolution, and dynamics of galaxies, shedding light on the processes that shape the cosmos. It allows us to probe the mysteries of dark matter and dark energy, understand the origins of stars and planets, and explore the potential for life beyond Earth.

Our Galaxy

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Our galaxy, known as the Milky Way, is a spectacular celestial phenomenon that enchants observers with its vastness and beauty. It spans an immense distance of about 100,000 light-years and comprises billions of stars, along with interstellar gas and dust. A stunning spiral galaxy, the Milky Way boasts a mesmerising structure, with a central bulge surrounded by a flattened disk of stars, gas, and dust. Radiating outwards from the bulge are magnificent spiral arms, each adorned with stellar clusters, nebulae, and other celestial wonders.

Nestled within one of these spiral arms, our solar system finds its home. From our position within the galaxy, we are afforded a breathtaking view of the cosmos, as we peer into the depths of space and marvel at the myriad stars and galaxies that populate our galactic neighbourhood.

The Milky Way is a dynamic and ever-evolving entity, with stars tracing graceful orbits around its centre. Over eons of time, these stars interact, forming clusters, binary systems, and occasionally experiencing cataclysmic events such as supernovae and black hole mergers.

Furthermore, the Milky Way is not an isolated entity but rather part of a vast cosmic ensemble, bound together by the force of gravity. As we explore the universe with increasingly powerful telescopes and instruments, we gain insights into the interconnectedness of galaxies and the intricate tapestry of the cosmos.

Studying our galaxy opens a window into the mysteries of the universe, offering clues about its origins, evolution, and ultimate fate. It allows us to ponder the enigmatic phenomena of dark matter and dark energy, contemplate the formation of stars and planets, and speculate about the possibility of life beyond our solar system.

In conclusion, the Milky Way stands as a testament to the grandeur and complexity of the universe, inspiring wonder and curiosity in all who contemplate its splendour. By studying our galaxy, we embark on a journey of discovery, deepening our understanding of the cosmos and our place within it.

Aeroplane Wing

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For a wing to work, it has to move through air to produce lift. A bird uses muscles, planes have engines – propellers or jet engines. Engines pull the plane through the air at high speed. Because of a wing’s special curved shape, the air flowing over a wing experiences a pressure difference between the upper and the lower surfaces, producing an upward force called lift, which is greater than the weight of the plane.

As a plane flies faster, it’s resistance in the air, called drag, increases, but the lift of the wing increases, allowing the plane to fly. So the four forces acting on a flying plane are: thrust from the engines; weight of the plane, drag (air resistance of the whole plane), and lift from the wings.

There is a minimum speed before the lift is greater than the weight of the plane which is why a plane needs a long runway before it can ‘take off’. Once in the air, the ailerons on the wings allow the pilot to control the direction of flight.

The flaps allow the wing to change its shape so that it can produce more lift, but that increases the drag. Flaps are extended during take-off and landing to produce more lift at lower speed, but are retracted during flight to reduce the drag.

A wing has to be designed to be as large as possible, but as light as possible, requiring a strong skeleton with a strong skin. The cavity is used for the fuel tanks which helps keep the centre of gravity in the middle of the plane for stability in flight.

Aeroplane Landing Gear

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The landing gear of an aeroplane, also called the undercarriage, is a complex system consisting of structural members, hydraulics, energy absorption components, brakes, wheels and tyres. Additional components attached to and functioning with the landing gear may include steering devices (front wheel) and retracting mechanisms.

The gear must be strong enough to support the heavy weight on take-off, when an aircraft has a full load of fuel, and then the high impact loads on landing. The landing gear, like everything else on a plane, must also be as light as possible, therefore special metals (e.g. titanium) and high strength alloys are often used. During flight hydraulic mechanisms retract the landing gear into recesses in the underside of the fuselage closed with hydraulic doors.

While take-off is a smooth progressive event, landing is particularly violent event. The wheels have to accelerate to over 200 kph on contact with the runway surface, scrubbing rubber off the tyres; the shock absorbers have to withstand the impact of landing and the brakes have to slow the plane down to a speed for taxiing. The tyres have many more layers than regular vehicle tyres and the brakes are actually clusters of multiple disc brakes which require a long cooling time before they can be used again. The landing gear require regular inspection and replacement of worn tyres and brake elements.

Aeroplane Cockpit

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The cockpit is the cabin at the front of the plane where the pilot (and co-pilot) fly the plane. They are the only people with a forward-looking view and even that is restricted. Because planes travel in three dimensions pilots require instruments showing the plane’s altitude (ALT, height above ground), forward speed relative to the air (SPD), rate of climbing or descending, and also the plane’s attitude – nose up or down (pitch) and tilted left or right (roll).

To control the plane the pilot has a control column (yoke, joystick) which is connected to the ailerons on the wings and the elevators. Turning the wheel rolls the plane left or right; pulling or pushing causes the plane to climb or descend. The pilot also has two coupled pedals connected to the rear vertical stabilizer. The controls for the engines are in the middle of the cockpit accessible by either pilot.

For navigation the pilot has a compass (HDG) for direction and a system of radio beacons as selectable landmarks. These days GPS (Global Positioning Systems) or SatNav (Satellite Navigation) perform these functions and have greatly simplified navigation and also allow auto-pilot systems to perform more in-flight control. Also in the cockpit are radar to detect and display weather conditions, controls for the flaps and landing gear, and many other instruments.

To assist with landing there are ground-mounted coloured lights and a directional radio signal to guide the pilot down to the runway. Both pilots wear a headset and communicate with other airplanes and the control towers on the ground by radio. They use a very specific vocabulary to avoid misunderstandings. Consequences of mistakes are enormous.

Aeroplane Fuselage

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The fuselage is the main body of an aeroplane to which everything else is attached. It is a long hollow tube, made as light as possible, yet strong enough to withstand the extremely low pressure and sub-zero temperatures outside the plane when flying at altitude.

A passenger plane needs a wide fuselage to provide space for many passengers and luggage, but that increases the drag and limits the maximum speed. Whereas a supersonic fighter plane, which requires little space for its heavy payload, has a slender streamlined fuselage which allows it to fly much faster.

On an airliner, the pilots sit in a cockpit at the front of the fuselage; the main fuselage carries passengers and cargo; fuel is stored in the wings to which the engines are attached; and the tail section carries the stabilizer fins and rudder.

Structural considerations are: the large forces where the wings are attached to the fuselage; window sizes are limited due to the pressure differences and pressure changes; the doors require special seals and locking mechanisms. For passenger aircraft the interior of the plane must be pressurised and air-conditioned.

Because the consequences of aircraft failures can be so extreme, planes have to be stripped down at regular intervals to check for cracks on all the structural members.

Aeroplane Engine

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Jet engine
A turbojet engine is a gas turbine engine that works by compressing intake air with a multi-stage compressor (axial, centrifugal, or both), injecting fuel into the compressed air and burning the mixture in a combustion chamber. The hot, high pressure, exhaust gas passes through a turbine, which drives the inlet compressor, and out the exhaust nozzle. So the engine converts the chemical energy in the fuel to kinetic energy in the exhaust, producing thrust. In a turbojet engine all the inlet air passes through the compressor, combustor, and turbine.

Whereas a turbofan engine has a large inlet fan which accelerates additional air in a duct surrounding the jet engine to produce extra thrust. Turbofans are the dominant engine for medium and long-range airliners.

Turbofans are usually more efficient than turbojets at subsonic speeds, but at high speeds their large frontal area generates more drag. Therefore, for supersonic flight, and in military and other aircraft, where other considerations have a higher priority than fuel efficiency, fans tend to be smaller or absent.

Turbofan engines are categorized as low-bypass or high-bypass, depending upon the amount of air which bypasses the core of the engine. Low-bypass turbofans have a bypass ratio around 2:1 or less.

Turbines have superior power-to-weight ratios than piston engines, and are more reliable for continuous high outputs. Turbines also work better than a naturally-aspirated piston engines at high altitudes and cold temperatures. Their light-weight build, reliability, and high-altitude capability makes turbines the engine of choice for airplanes. Turbines are also commonly used at power plants for electricity generation (hyperlink).

Plants (plant biodiversity /categorisation)

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Plants are an integral component of our planet's ecosystem, playing a vital role in sustaining life as we know it. From the towering trees of the Amazon rainforest to the delicate wildflowers of the British countryside, plant life encompasses an astonishing array of forms, functions, and adaptations. Understanding plant biodiversity and categorisation is essential for appreciating the complexity and beauty of the natural world.

Plant biodiversity refers to the rich variety of plant species coexisting in different environments around the globe. It encompasses not only the vast array of species but also their genetic diversity within each species. This diversity ensures resilience and adaptability in the face of environmental changes, making it crucial for the health and stability of ecosystems.

Scientists categorise plants into various groups based on shared characteristics, allowing us to organise and understand this diversity more effectively. One of the primary classifications divides plants into flowering plants (angiosperms) and non-flowering plants (gymnosperms and ferns). Flowering plants, the most diverse group, produce seeds enclosed within fruits and flowers and dominate terrestrial ecosystems worldwide. Non-flowering plants include gymnosperms, such as conifers and cycads, which bear seeds in cones, and ferns, which reproduce via spores.

Beyond these broad categories, plants are further classified into smaller groups based on characteristics such as leaf structure, reproductive methods, and evolutionary relationships. Mosses, liverworts, and algae represent additional groups, each with distinct adaptations enabling them to thrive in specific habitats and environmental conditions.

Studying plant biodiversity and categorisation provides valuable insights into ecosystem dynamics, species interactions, and environmental changes over time. It helps scientists monitor shifts in plant populations, track the impacts of human activities such as deforestation and climate change, and identify areas of conservation priority.

Moreover, understanding plant diversity enriches our appreciation of the natural world and fosters a sense of stewardship for the environment. It inspires curiosity and wonder, encouraging individuals of all ages to explore and connect with the plants that surround them.

Internal Combustion Engine

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The typical car engine shown here is a 4-stroke petrol engine. The chemical energy from burning petrol causes an explosion inside the engine that forces a piston to slide down inside a cylinder. The piston is connected to a crankshaft, and this mechanical energy is transferred through a gearbox to the drive wheels of the car. The four strokes of the engine are:
• Inlet - piston moves down and sucks in air and petrol (from carburettor or fuel injector)
• Compression – piston moves up and compresses the gas mixture
• Power – the spark ignites the mixture and the explosion forces the piston to down
• Exhaust – the piston rises and forces the burnt gases into the exhaust manifold

One piston/cylinder on its own cannot work well. Four cylinders arranged so that one at a time is on a power stroke, provide a smoother and more continuous power output.

A piston engine is incredibly responsive, and more fuel-efficient over a wide power range. This makes piston engines ideal for use in vehicles and explains why, despite poor fuel efficiency and exhaust gases, they are still in use after 125 years.

Substantial improvements in fuel economy have been achieved with sophisticated electronic controls, sensors and direct fuel injection. The toxicity of exhaust gases has been reduced with the introduction of catalytic converters (link).

A diesel-fuelled engine works is a similar way. It is generally more fuel-efficient but has more toxic exhaust gases. Its performance favours specific applications, typically heavy-duty.

Braking System

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A good braking system is essential for stopping your vehicle. Pressing the brake pedal, which is attached, via levers, to the master cylinder, applies pressure to brake fluid, within a network of hydraulic pipes, connected to actuators on the actual brakes at each wheel. The more force a driver applies to the brake pedal, the higher the stopping force that is applied at the wheels. The master cylinder has a reservoir that keeps the system full of brake fluid.

Disk brakes use pads lined with friction material to grab a steel disk that is rotating with one of the road wheels whereas drum brakes have brake ‘shoes’, also lined with friction material, that are pushed against the inside of a rotating drum inside a road wheel.

Front brakes play a greater part in stopping a car than the rear ones because braking throws the car weight forward on to the front wheels. Many vehicles, therefore, have disc brakes, which are generally more efficient, at the front and drum brakes at the rear. The handbrake, which is also considered an emergency brake, is usually connected to the rear brakes by steel cables.

The force applied to the brakes can be boosted by a ‘servo’ that uses either engine vacuum or hydraulic pressure to amplify the force from the master cylinder, so the driver does not have to push the pedal as hard.

In addition to this primary braking system, most modern vehicles are fitted with an electronic Anti-lock Brake System (ABS) to prevent skidding. The ABS can detect any wheel skidding (through electronic sensors) and adjust the braking force on any wheel (using high-pressure pumps). It allows you to brake as hard as possible, and slow down as quickly as possible, during an emergency stop.

Steering System

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A steering system is required to allow the driver to aim the vehicle in the direction of travel by turning the front wheels. The steering wheel in the car is connected to the two front wheels by a combination of gears and levers. To improve the accuracy of the mechanism and to reduce the effort required at the steering wheel, it takes a significant rotation of the steering wheel to make a small change in the angle of direction of the front wheels.

The suspension system is cleverly designed to allow each wheel to move up and down without changing the steering angle. Therefore most of the steering joints have to be ‘knuckle’ or ball-joints.

The system must also ensure that, when cornering, the inner front wheel - which has to travel around a tighter curve than the outer one - becomes more sharply angled. If the steering system gets worn or out of alignment, the tyres will wear out much faster. See suspension system for more details on caster and camber angles.

Most modern cars are fitted with a hydraulic pump to increase the force applied into the steering mechanism and onto the wheels. The hydraulic pumps system reduces the effort that is required to turn the steering wheel.

Car Exhaust System

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The exhaust system is the piping and devices that the burnt gases from the engine travel through before discharging into fresh air. Depending on the system design, the exhaust gas will flow through the following:
• Cylinder head and exhaust manifold on the engine
• A turbocharger (hyperlink) to increase engine power.
• A catalytic converter to reduce air pollution.
• A silencer/muffler (USA) to reduce noise.

An exhaust pipe is designed to carry hot, toxic and noxious gases (including carbon monoxide and oxides of nitrogen) away from the occupants of the car and dilute them into the general atmosphere. The pipe must be heat-resistant, and it must be kept away from anything that can burn or be damaged by heat. For an internal combustion engine the exhaust system has to be "tuned" to prevent the shock waves from colliding. Most countries have regulations setting the limits on gas concentrations in the final exhaust.

Turbocharger: recovers energy from the exhaust gas, to drive a small gas turbine (‘turbo’), coupled to a gas compressor, to boost the pressure of the air going into the engine and improve its power and efficiency.
Catalytic converter: Contains a fine honeycomb mesh, with a large surface area, plated with platinum/palladium/rhodium that converts some of the poisonous exhaust gases into less harmful gases e.g. NO2 into NO,
Silencer/Muffler: a box with sound-absorbing material and baffles to reduce the noise of the final exhaust to atmosphere.
Oxygen (O2) sensors: in modern cars, by monitoring the exhaust gases, the fuel injection system can be finely tuned to optimise combustion in the engine and to minimise harmful gases in the exhaust.

Car Aircon System

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The air conditioning system operates similarly to a refrigerator, using a compressor and a refrigerant gas to remove heat from the air inside the car and release it outside the vehicle. The system has six main components:
· The refrigerant is the gas/liquid that transports the heat and also carries the oil for lubricating the compressor and expansion valve. Common refrigerants used in vehicles are R1234yf, R134a and R12. Some are being phased out for environmental reasons (global warming).
· The compressor draws low-pressure refrigerant gas from the cold evaporator, compresses it and pumps it to the outside condenser radiator. The compressor is driven by a belt off the car’s engine. The compressor starts and stops using an electro-magnetic clutch to engage/disengage the compressor.
· The condenser is the outside radiator where the hot refrigerant gas cools down and condenses back to a liquid.
· The expansion valve (or orifice tube) controls/restricts the flow of the refrigerant liquid from the high-pressure condenser back to the low-pressure evaporator, according to the temperature setting. This is where the refrigerant cools down.

· The evaporator is the cold radiator inside the car that cools the air blown across it by a fan – either fresh air from outside or recirculated air. Here the refrigerant absorbs heat and boils back to a gas. The suction of the compressor creates low pressure.

· The receiver dryer or accumulator is a small storage vessel that contains a desiccant substance to remove any moisture from the refrigerant.

When you start the ‘air-con’ system, the compressor causes low pressure in the evaporator, making it cold. The compressor sends the hot gas to the condenser radiator, which is generally in front of your vehicle’s radiator. The heat is released outside the of the car, and the refrigerant condenses from a gas back to liquid, which then passes through the expansion valve back to the evaporator. This is a continuous cycle.

For heating the air inside the car, there is another radiator that uses hot water from the engine’s cooling system. The control panel in the vehicle allows you to choose the system and set the temperatures for the current conditions. In modern cars, this is highly automated.

Insects

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Insects are small air-breathing arthropods (such as ants, beetles, butterflies, bees) with a three-part body (head, thorax and abdomen), three pairs of jointed legs, typically one or two pairs of wings, compound eyes and two antennae.

Insects are the most diverse group of animals; they include more than a million described species and represent more than half of all known living organisms and over 90% of the animal life forms on Earth. Insects are found in nearly all land environments, but only a few species reside in the oceans. Insects perform a vital role in supporting other life forms and ecosystems; pollination, soil aeration, processing of nutrients and as part of the overall food chain.

Entomology is the study of insects and their relationship to humans, the environment, and other organisms. Entomologists contribute to such diverse fields as agriculture, chemistry, biology, human/animal health, molecular science, and even criminology and forensics.

Plant-parasitic nematode feeding types.

Nematology

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Nematodes, also known as roundworms and eelworms, are one of the most diverse and abundant groups of animals on earth. They are found on every continent and in almost every habitat known to man. Nematodes in the soil are microscopic organisms and can very rarely be seen with the naked eye. There are many different kinds of nematodes and they are divided into groups based on what they eat. Herbivorous nematodes (plant-parasitic nematodes), feed on all different parts of a plant. These nematodes are sometimes referred to as the bad nematodes because they can cause damage to agricultural crops and they make it difficult to grow the food we eat.

But there are also beneficial nematodes, the so called good guys, which can be beneficial to humans because they are essential for soil health. These nematodes are also divided into different groups. Bacterivores (nematodes that eat bacteria), fungivores (nematodes that eat fungi), predators (nematodes that eat other microscopic animals including other nematodes) and omnivores (nematodes that eat plants and animals). These nematodes play an essential role in the soil food web because not only do they eat the other organisms in the soil, but they are also food for many of the other animals also found in the soil. Nematodes are also important in nutrient cycling in the soil, enabling plants to take up nutrients and ensuring plant growth. In the soil environment there are millions of nematodes from all the different feeding groups.

A sac spider, Cheiracanthium species, that can be found on different crops. Photograph by Peter Webb.

Spider

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Spiders are one of the most common predator groups in South African agricultural ecosystems. This means they are abundant predators occurring on various crops, including orchards. They are considered to be natural control agents against pests and mites occurring on crops.

How are spiders able to help control pests and mites?
- Spiders are present on crops throughout the year. Their lifespan, that vary from species to species, have instars or juveniles stages that actively feed as predators. Food consumption decreases only before and during ecdysis. Ecdysis is the process where the spiders moult and shed their exoskeletons.

- The fact that spiders are usually polyphagous helps them to act as a natural control agents for pests and mites. Polyphagus means that spiders feed on a variety of available prey. They do not feed on adult prey only, but on different stages of the insect or mite. Research has shown that spiders are often some of the first predators to arrive and colonise a newly planted crop, which is important as many pests attack in the early stages of the crop during the growing season.

- Different species of spiders are found in different microhabitats. Wandering spiders live on the ground and they feed mainly on ground-living insects and larvae hibernating in the soil. The plant-dwelling spiders are present on the stems, foliage, bark or flowers of plants. Many of them are active hunters and move around in search of prey. A number of web-building spiders spin their webs between the leaves and branches, under the bark and even over the leaf surfaces. They will prey on insects that come into contact with the silk threads of their webs.

- As predators, spiders have a two-fold effect. Not only do they feed directly on their prey, but their presence also causes indirect mortality. For example, the presence of foraging spiders can disturb insect larvae, which then drop from the plant and die, or are exposed to predation by ground dwelling predators. The webs spun over the leaves also seem to make them less suitable for oviposition and feeding by pests.

Animal Biology (zoology)

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States of matter

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Lunch Box

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Vase

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Food pyramid

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Phases of the moon

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Rock (geology)

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Fossils

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Wire toy car

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Living and Non-living Things: - Living things - Non-living things

Structure of Plants and Animals: - Structure of plants - Structure of animals

What Plants Need to Grow: - Conditions for growth

Habitats of Animals: - Different habitats - Need for a habitat

Structures for Animal Shelters: - Animal shelters

Strengthening Materials: - Ways to strengthen materials

Strong Frame Structures: - Struts and frame structures - Indigenous structures

Materials Around Us: - Solids, liquids and gases - Change of state - The water cycle

Solid Materials: - Raw and manufactured materials - Properties of materials

Energy and Energy Transfer: - Energy for life - Energy from the Sun

Energy Around Us: - Energy - Input and output energy

Energy and Sound: - Vibrations and sound - Making sounds - Noise pollution

Movement and Energy in a System: - Movement and musical instruments

Rocket Systems: - Modelling a rocket

Planet Earth: - Features of the Earth - Earth and space

The Sun: - Our closest star

The Earth and the Sun: - Moving around the Sun - The Sun and life

The Moon: - Features of the Moon - Phases of the Moon - Moon stories

Stored Energy in Fuels: - Fuels - Burning fuels -Safety with fire

Energy and Electricty: - Cells and batteries - Mains electricity - Safety with electricity

Energy and Movement: - Elastic and springs

Skeletons as Structures: - Frame and shell structures

Metals and Non-metals: - Properties of metals - Properties of non-metals

Uses of Metals: - Other properties of metals - Uses of metals

Processing Materials: - Combining materials

Processed Materials: - Properties and uses - Traditional processing

Systems for Moving Things: - Wheels and axles

Planet Earth: - The Earth moves

Surface of the Earth: - Rocks - Soil types

Sedimentary Rocks: - Formation of sedimentary rock - Uses of sedimentary rock

Fossils: - Fossils in rock - Body and trace fossils - Importance of South African fossils

Photosynthesis: - Plants and food - Plants and air

Nutrients in Food: - Food groups - Balanced diets

Ecosystems and Food Webs: - Different ecosystems - Living and non-living things in ecosystems - Food Webs

Solids, Liquids and Gases: - Arrangement of particles

Mixtures: - Mixtures of materials

Mixtures and Water Resources: - Water pollution - Importance of wetlands

Solutions as Special Mixtures: - Solutions - Soluble substances - Saturated solutions - Insoluble substances

Dissolving: - Rates of dissolving

Electric Circuits: - A simple circuit - Circuit diagrams

Electrical Conductors and Insulators: - Conductors - Insulators

Mains Electricity: - Fossil fuels and electricity - Cost of electricity - Illegal connections

Systems to Solve Problems: - Using electric circuits

Systems to Explore the Moon and Mars: - Vehicles used on the Moon - Vheicles used on Mars

Systems for Looking into Space: - Telescopes

The Solar System: - The Sun, planets and asteroids - Moons

Movement of the Earth and the Planets: - Rotation (Earth) - Revolution (Earth)

The Movement of the Moon: - Rotation (Moon) - Revolution (Moon)

Food Processing: - Need for processing food - Methods for processing food

Processes to Purify Water: - Clean water

Grade 4: Matter and materials

Curriculum

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Materials around us

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Solids, liquids and gases

• solids, liquids and gases make up all the materials around us
• some properties of solids, liquids and gases
• solids keep their shape
• liquids flow and take the shape of their container
• gases, such as air, tend to spread out, have no definite shape but can be contained (like in a balloon)

Change of state

• heating and cooling (removing heat) cause solids, liquids and gases to change state
• a solid first changes to a liquid (melting) when heated and then the liquid changes to a gas (evaporating) on further heating
• gas first changes to a liquid (condensing) when cooled and then the liquid changes to a solid (freezing/solidifying) when cooled further

The water cycle

• water evaporates, condenses, freezes and melts in the water cycle

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Suggested Activities

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• sorting examples of common materials into solids, liquids and gases including wood, stone, plastic, fabric, water, juice, tea, air, cooking oil, cooking gas, and describing them
• Investigating evaporating, condensing, freezing and melting using water and ice
• Investigating melting and solidifying using different substances such as butter/ fat/ margarine, wax, icecream, chocolate
• drawing and writing about the water cycle

Grade 5: Life and Living and Structures

Curriculum

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Animal skeletons

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Skeletons of vertebrates

• a vertebrate skeleton consists of bones and joints, and is inside the body
• bones are hard and form a strong frame structure
• a skeleton provides support for an animal’s body and protection for its organs;
• skull - protects the brain
• backbone with vertebrae - protects the spinal cord
• ribs - protect the lungs and heart
• shoulder blades, arms, legs, hip bones – for movement

Movement

• vertebrate animals can move because there are
• muscles attached to the skeleton
• joints between the bones***

Skeletons as structures
Frame and shell structures

• a vertebrate skeleton is a frame structure (also refer to grade 4 Matter & Materials)
• some invertebrate skeletons are shell structures such as that of a crab

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Suggested Activities

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• looking at examples of skeletons including
  • fish, frogs, birds, reptiles, mammals (including humans), and identifying the following parts:
  • the skull
  • the backbone
  • ribs
  • limbs
  • shoulder and hip girdles**
• describing how different vertebrate animals move (including humans)
• making a model* of a vertebrate skeleton using struts made from rolled paper or drinking straws [This can be used as a possible project]

* This is a problem solving activity, where learners have to work out how a skeleton fits together

Whale in the museum


Dinosaur outside the museum

Grade 5: Planet Earth and Beyond

Curriculum

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Fossils

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Fossils in rock

• fossils are the remains of ancient plants and animals preserved in rock
• fossils are found in some layers of sedimentary rock
• fossils are evidence, a record of the history of life on Earth
• there are two main types of fossils; body and trace fossils

Body and trace fossils

• body fossils form from the hard parts of plant and animal bodies including teeth, bones, shells, stems, leaves and seeds
• trace fossils form from traces left by animals including footprints, nests, eggs and droppings
• some features of fossils resemble the features of plants and animals living today

Importance of South African fossils

• South Africa has a particularly rich fossil record of plants, animals and early humans
• important fossils found in South Africa include the Coelacanth and African dinosaurs
• the “Cradle of humankind” is one of the sites where important fossils of humankind have been found in South Africa

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Suggested Activities

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• making a model to show the layers of sedimentary rocks with fossils embedded in them (using a medium such as play dough, clay, plaster of Paris, and remains of living things such as leaves, shells and bones)
• interpreting pictures of fossils and comparing them to plants and animals living today
• reading about fossils including the Coelacanth and African dinosaurs

A close-up of a fossilized dinosaur embryo


A reconstruction of the Massospondylus
dinosaur from fossil remains

Grade 4: Energy and change

Curriculum

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Energy and change

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Energy and sound
Vibrations and sound

• musical instruments make sounds through vibrations
• the sound always moves outwards from the part that is vibrating
• we can feel or hear vibrations
• vibrations travel through materials such as air, water, plastic, metal and wood

Making sounds

• sounds can be made loud or soft (volume)
• sounds can be made high or low (pitch)

Noise pollution

• sound that is loud, unpleasant or harmful to our ears and continues for a long time, is described as noise pollution
• noise pollution can cause permanent damage to hearing (hearing aids can help people who are hearing-impaired)

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Suggested Activities

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• looking at pictures of the human ear, its parts and how sound travels through it
• making loud and soft sounds with your voice and/or musical instruments
• making high and low pitched sounds with your voice and/or musical instruments
• describing sources of noise pollution including at home, school, in the community and how best to protect ourselves from it

Grade 5: Life and Living

Curriculum

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Plants and animals on earth

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Plants and animals on earth
Many different plants and animals
• there are many different plants and animals living in different habitats on Earth
* (South Africa has a wide variety of indigenous plants and animals and their habitats)
Inter-dependence

• plants and animals depend on each other
• they also depend on the resources available (such as air, water, soil, food, and places to hide) in their own habitats

Animal types

• there are many different kinds of animals,
  • some do not have bones, and some have hard outer ‘skins’ or shells (invertebrates)
  • some have bones (vertebrates)

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Suggested Activities

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• counting the number of plants in a given area and distinguishing them apart by looking at the shapes and colours of their leaves or flowers or fruits
• describing
  • animals without bones, such as worms, millipedes, insects, spiders, scorpions, crabs
  • animals with bones, such as fish, frogs, reptiles, birds, mammals

[* Plants and animals, and their habitats make up the total biodiversity of the Earth]

See the spider spinning its web on the Nature tile


Watch the plant grow on the Agriculture tile


Visit Animal World to learn about penguins

Grade 5: Systems and control

Curriculum

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Systems and control

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Wheels and axles

• many vehicles are systems that use wheels and axles
• wheels and axles help vehicles to move more easily

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Suggested Activities

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• identifying different vehicles that have wheels and axles including prams, bicycles, motor bikes, cars, trucks
• making wheels and axles and evaluating whether they move easily (use materials such as bottle tops, round tins or cardboard circles for the wheels, sosatie sticks or dowels and straws for the axles)

Steering wheel system of a car


Landing gear of an aeroplane

Grade 6: Energy and change

Curriculum

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Mains: Electricity

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Fossil fuels and electricity

• fossil fuels were formed in the Earth’s crust millions of years ago from dead plants and animals
• coal, oil and natural gas are fossil fuels
• in South Africa coal is mostly used as a fuel in power stations
• coal was formed from fossilised plants which got their energy from the Sun originally
• in a power station coal is used to boil water, the steam turns a turbine which turns a generator, which produces electricity
• fossil fuels are non-renewable resources

Cost of electricity

• electricity is costly because
• it requires infrastructure including coal mines, transport, power stations, pylons, substations, wiring
• some electrical appliances require more electricity than others (heating appliances use the most)
• the more electricity we use, the more we pay and the more coal is used up
• we can save energy in many ways including using energy saving light bulbs and solar water heaters

Illegal connections

• illegal electrical connections are a danger to people because they are often unsafe

Renewable ways to generate electricity

• people are looking for renewable ways to generate electricity

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Suggested Activities

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• drawing and writing about to explain how fossil fuels such as coal were formed
• drawing and writing to trace the electrical energy in a sequence from an appliance, such as from your TV set, to the coal-fired power station and back to the original source, the Sun
• examining labels (in adverts, or real electrical appliances) to find out how much power they require (most kettles require more than 2000 W, whilst a radio might require about 15 W*). Recording findings on a table
• Researching and writing about renewable ways to generate electricity including in wind power generators, solar panels (photovoltaics)**, hydro-electric power generators

Click on the power icon on the house page
to see the grid of electricity in the house